This research proposal entitled "Therapeutic strategies in Chronic lymphocytic leukemia with curative intent "is in response to RFA CA-94- 014:"Investigator Grants for Clinical Cancer Therapy Research". Chronic lymphocytic leukemia (CLL), the most frequent type of leukemia in Western countries is manifested by the accumulation of mature appearing CD5, CD19 and CD2O positive, immunologically incompetent lymphocytes in the blood, bone marrow, lymph nodes and spleen with gradual marrow failure. High risk patients have a poor median life expectancy of 2 years with standard therapy. Newer modalities of treatment are therefore warranted in this disease. The overall aim of this proposal is to develop a curative therapeutic program for CLL using sequential high dose cytotoxic therapy followed by biologic manipulation of the residual malignant clone. In order to determine the efficacy of such therapeutic approaches, we propose to assess minimal residual disease utilizing two techniques: l) three color flow cytometry assessing kappa/lambda clonal excess on CD5/CD19 dual staining cells and 2) a novel clonotypic polymerase chain reaction (pCR) assay using clone specific primers of the VH-D-JH rearrangement of the immunoglobulin heavy chain gene. High dose therapy followed by stem cell rescue has recently appeared promising as a component to "curative" therapy in a number of malignant conditions. The major problem at present to this approach is the contamination of the autograft by malignant cells, which contribute to subsequent disease recurrence. We plan to apply recently developed immunologic purging strategies to isolate Soybean agglutinin negative (SBA-)CD34+CD2O-CD19-CD5- purified hematopoietic progenitor cells, from either the bone marrow (post cytoreductive therapy) or peripheral blood (chemotherapy plus hematopoietic growth factor mobilized peripheral blood progenitor cells (PBSC)), from patients with CLL. The absence of tumor cell contamination of isolated progenitors will be evaluated by both flow cytometry and the clonotypic PCR assay. This strategy will allow us to assess the feasibility of procuring adequate numbers of purified progenitors to enable us to pursue autologous stem cell support in CLL following myeloablative chemoradiotherapy.